Qualifies for the billionaire ranks as a son of slain Lebanese prime minister Rafik , who left behind a $16.7 billion estate last year. Now based in Riyadh, helps watch over family holding company Saudi Oger for older brother Saad Hariri, Lebanese parliamentary majority leader. Also has hands in U.S. government contracting: cofounded and chairs identity management software firm Epok, based outside Washington, D.C., which aims to sell to federal and state customers.